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朴哲圓(Chul-Won Park),申光哲(Kwang-Chul Shin),申明澈(Myong-Chul Shin) 대한전기학회 2008 전기학회논문지 P Vol.57 No.2
AC generator plays an important role of power system. The large AC generator fault may lead to large impacts or perturbations in power system. And then the protection of a generator has very important role in maintaining stability in a power system. In present, the DFT(discrete Fourier transform) based RDR(ratio differential relay) had been widely applied to a internal fault of a generator stator winding. But DFT has a serious drawback. In the course of transforming a target signal to frequency domain, time information is lost, DWT uses a time-scale region. This paper proposes an advanced fault detection algorithm using DWT(discrete Wavelet transform) to enhance the drawback of conventional DFT based relaying. To evaluate the performance of the proposed relaying, we used the test data which were sampled with 720 [㎐] per cycle and obtained from ATP(alternative transient program) simulation. And we made a comparative study of conventional DFT based RDR and the proposed relaying.
다우비시 웨이브릿 변환의 상세계수 비율을 이용한 교류발전기의 내부고장 검출 및 고장종류 판별
박철원(Chul-Won Park),신광철(Kwang-Chul Shin),신명철(Myong-Chul Shin) 대한전기학회 2009 전기학회논문지 P Vol.58 No.2
An AC generator is an important components in producing a electric power and so it requires highly reliable protection relays to minimize the possibility of demage occurring under fault conditions. Conventionally, a DFT based RDR has been used for protecting the generator stator winding. However, when DFTs based on Fourier analysis are used, it has been pointed out that defects can occur during the process of transforming a time domain signal into a frequency domain one which can lead to loss of time domain information. This paper proposes the internal fault detection and fault type discrimination for the stator winding by applying the detailed coefficients by Daubechies Wavelet Transform to overcome the defects in the DFT process. For the case studies reported in the paper, a model system was established for the simulations utilizing the ATP, and this verified the effectiveness of the proposed technique through various off-line tests carried out on the collected data. The propose method is shown to be able to rapidly identify internal fault and did not operate a miss-operation for all the external fault tested.
박철원(Chul-Won Park),신광철(Kwang-Chul Shin),신명철(Myong-Chul Shin) 대한전기학회 2008 대한전기학회 학술대회 논문집 Vol.2008 No.11
전통적인 FT(Fourier Transform)의 대안으로 scale과 shift에 의한 WT(Wavelet Transform)이 제안되어, 전력계통의 각 분야에 적당한 Mother Wavelet 선택에 대한 연구가 시도되고 있다. 본 논문은 발전기 고정자 사고의 경우 고장판별을 위하여 적당한 마더 웨이브릿을 선정할 수 있는 알고리즘에 관한 것이다. ATP 시뮬레이션으로부터 수집한 전류데이터를 이용하여 제안된 적당한 선정기법의 유효성을 증명하였다.